UScholar Works
 
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CreatorTitleDescriptionSubjectDate
576 Symko, Orest George; Vardeny, Zeev ValentineFemtosecond dynamics of quasi-particles in YBa2Cu3O7-δ superconductor filmsWe have studied the transient electronic response of YBa2Cu30y . 5 epitaxialy grown HTC superconductor thin films in the femtosecond time domain, using transient photoinduced reflectivity (∆R) with 60 fsec time resolution. For temperatures T>TC only a bolometric signal was observed with ∆R>0. F...Femtosecond dynamics; Superconductor films; YBCO films1991-03
577 Vardeny, Zeev ValentineFemtosecond dynamics of the nonlinear optical response in polydiethynylsilaneWe have measured the femtosecond dynamics of the nonlinear optical response xc3' in polydiethynylsilane ( C4H2SiBu2)x, a novel class of r-conjugated polymers incorporating Si, using degenerate four-wave mixing and photoinduced absorption techniques. In resonance conditions at 620 nm we found x (3) ...Polydiethynylsilane; Femtosecond dynamics; Nonlinear optical response; Pi-conjugated polymers1991
578 Symko, Orest George; Vardeny, Zeev ValentineFemtosecond optical detection of quasiparticle dynamics in high-Tc YBa2Cu3O7- 8 superconducting thin filmsFemtosecond dynamics of photogenerated quasiparticles in YBa2Cu307-δ superconducting thin films shows at T ≤ Tc two main electronic processes: (i) quasiparticle avalanche production during hot-carrier thermalization, which takes about 300 fsec; (ii) recombination of quasiparticles to form Cooper ...Quasiparticle dynamics; High-Tc; Femtosecond dynamics; Photogenerated quasiparticles1990-11
579 Vardeny, Zeev Valentine; Symko, Orest GeorgeFemtosecond optical detection of quasiparticle dynamics in High-Tc YBa2Cu3O7-δ superconducting thin filmsFemtosecond dynamics of photogenerated quasiparticles in YBa2Cu307-δ superconducting thin films shows at r < Tc two main electronic processes: (i) quasiparticle avalanche production during hot-carrier thermalization, which takes about 300 fsec; (ii) recombination of quasiparticles to form Cooper pa...Femtosecond optical detection; HTc YBa2Cu3O7-81990-11
580 Miller, Joel StevenFerrimagnetic ordering of a methylthio-substituted planar porphyrin based electron transfer salt, octakis(2,3,7,8,12,13,17,18-methylthio)porphyrinatomanganese(III) tetracyanoethanideThe direct redox reaction between tetracyanoethylene (TCNE) and a planar porphyrinatomanganese(II), octakis(2,3,7,8,12,13,17,18-methylthio)porphyrinatomanganese(II), MnIIOMTP, produced a polymeric electron transfer salt (ETS), that has been structurally and magnetically characterized. The ETS belon...Magnetic; Temperature; Coupling2000
581 Miller, Joel StevenFerrimagnetic ordering of one-dimensional N,N'-dicyanoquinone diimine (DCNQI) electron transfer salts with porphyrinatomanganese(II)*The redox reaction between N,N'-dicyanoquinone diimines (DCNQIs) and porphyrinatomanganese(II) produced electron transfer salts (ETSs), [MnIIITMesP]+[DMeO-DCNQI]-. 1 (MnIIITMesP=meso-tetrakis(2,4,6- trimethylphenyl)porphyrinatomanganese(III), DMeO-DCNQI=2,5-dimethoxy-N,N'-dicyanoquinone diimine) an...Transitions; Interactions; Magnetic2001
582 Miller, Joel Steven; Epstein, Arthur J.Ferrimagnetic resonance in films of vanadium [tetracyanoethanide]x, grown by chemical vapor depositionFerrimagnetic resonance (FMR) measurements in thin films of V[TCNE]x grown by chemical vapor deposition exhibit a series of sharp lines at 300 K. The orientational dependence of these lines is a result of the sample geometry provided the magnetization tracks the applied magnetic field. The FMR inten...Spin; Anisotropy; Magnetization2004
583 Miller, Joel Steven; Epstein, Arthur J.Ferromagnetic behavior and magnetic excitations in a molecular-based alternating-spin chain: decamethylchromocenium tetracyanoethenideWe report the study of magnetic properties of a molecular-based alternating-spin chain: metallocenium electron-transfer salt decamethylchromocenium tetracyanoethanide, [CrCp(*2)] [TCNE]. We give a modified spin-wave theory for the Heisenberg alternating-spin chains. The low-field susceptibility and...TCNE; Magnetization1994
584 Miller, Joel Steven; Epstein, Arthur J.Ferromagnetic behavior of decamethylchromocenium tetracyanoethenide, [CrCp*2][TCNE]Studies on the magnetic properties of decamethylchromocenium tetracyanoethanide, [CrCp*2][TCNE] are reported herein. Near-zero field (H= 150 mG) data indicates a ferromagnetic transition with T(c)=3.65 K. The temperature dependence below T(c) can be fit to a mean-field result M=M(o)(1 - T(o))(1/2)...Magnetic; Magnetization; Transition1993
585 Miller, Joel Steven; Epstein, Arthur J.Ferromagnetic properties of one-dimensional decamethylferrocenium tetracyanoethylenide (1:1): [Fe(n5-C5Me5)2].+[TCNE].-[Fe(C5Me5)2].+ [TCNE].-- has been characterized by magnetic susceptibility to possess dominant ferromagnetic interactions; its structure has been determined by X-ray crystallography.Susceptibility; Crystal; Magnetic1986
586 Mattis, Daniel C.Ferromagnetism and spin waves in the band theoryIntra-atomic exchange (Hund's rule mechanism) and Heisenberg nearest-neighbor exchange are examined for their role in the ferromagnetism of metals with degenerate bands. We examine the ground state, and find there is ferromagnetism once the largest eigenvalue j00 of the exchange matrix exceeds 1/2...Band theory; Hund's rule1963-12
587 Miller, Joel Steven; Epstein, Arthur J.Ferromagnetism in molecular decamethylferrocenium tetracyanoethylenide: (DMeFc TCNE)The temperature and magnetic field dependence of the magnetization and susceptibility of single-crystal decamethylferrocenium tetracyanoethenide demonstrate that this material is the first molecular compound with a ferromagnetic ground state. A spontaneous magnetization is observed for T < 4.8 K. T...Magnetization; Ferromagnetic1987
588 Miller, Joel Steven; Epstein, Arthur J.Ferromagnetism in molecular materials: decamethylferrocenium tetracyanoethanide [DMeFc][TCNE] (invited)Ferromagnetism has only recently been observed in molecular materials. We present here a summary of the ferromagnetic phenomena observed in the molecular charge transfer salt, decamethylferrocenium tetracyanoethanide (DMeFc) (TCNE), and related compounds. A spontaneous magnetization is observed i...Magnetic; Magnetization1988
589 Mattis, Daniel C.Few-body problem on a latticeThe author explores some of the inherent simplifications of "quantum lattice physics." He distinguishes between fermions and bosons and analyzes the n-body problem for each, with n = 1,2,3... typically a small number. With delta-function (zero-range) interactions, the three-body problem on a lattice...Quantum; Electrons; Spin1986
590 Moon, Ann M.; Capecchi, Mario R.Fgf8 is required for outgrowth and patterning of the limbs.The expression pattern and activity of fibroblast growth factor-8 (FGF8) in experimental assays indicate that it has important roles in limb development, but early embryonic lethality resulting from mutation of Fgf8 in the germ line of mice has prevented direct assessment of these roles. Here we rep...Animals; Body Patterning; Bone Morphogenetic Proteins; Ectoderm2000-12-26
591 Armentrout, Peter B.Fifty years of ion and neutral thermochemistry by mass spectrometryOriginating with the appearance potentials for "positive rays", the ability of mass spectrometry to obtain quantitative information about the energetics of both ions and neutrals has evolved dramatically. About 50 years ago, many of the techniques that are now common place were first implemented, th...2014-01-01
592 Vardeny, Zeev ValentineFilm morphology and photophysics of polyfluoreneWe have studied the interplay between photophysics and film morphology of poly(9,9-dioctyl)fluorene (PFO) using a variety of optical probes. Upon slowly warming a spin-cast PFO film from 80 to 300 K, a fraction of the sample is transformed into a different solid phase, the ß phase. Absorption and e...Polyfluorene; Photophysics; Film morphology2000-12
593 DeTar, CarletonFinite temperature lattice QCD with clover fermionsWe report on our simulation of finite temperature lattice QCD with two flavors of O(a) Symanzik-improved fermions and O(a2) Symanzik-improved glue. Our thermodynamic simulations were performed on an 83 × 4 lattice, and we have performed complementary zero temperature simulations on an 83 × 16 la...Wilson quarks; Clover fermions1997-02
594 DeTar, CarletonFinite temperature QCD: progress and outstanding problemsI review recent progress in numerical simulations of finite temperature quantum chromodynamics and discuss the status of some outstanding problems. Included is (1) a discussion of recent results determining the temperature of the "phase transition" in full QCD, (2) a scaling analysis of the Polyakov...Phase transitions; Staggered fermions; Wilson fermions; Polyakov loop; Deconfinement; Instanton1995-04
595 DeTar, CarletonFinite-size and quark mass effects on the QCD spectrum with two flavorsWe have carried out spectrum calculations with two flavors of dynamical Kogut-Susskind quarks on four lattice sizes from 83X24 to 163 X 24 at couplings that correspond to chiral symmetry restoration for a lattice with six time slices. We estimate that the linear spatial sizes of the lattices range f...Kogut-Susskind quarks; Hadron mass; Pion mass1993-11
596 DeTar, CarletonFirst determination of the strange and light quark masses from full lattice QCDWe compute the strange quark mass ms and the average of the u and d quark masses mˆ using full lattice QCD with three dynamical quarks combined with the experimental values for the rr and K masses. The simulations have degenerate u and d quarks with masses mu=md=mˆ αs low as ms/8, and two diffe...Staggered quarks; Quark-gluon plasma2004-08
597 Sokolsky, PierreFirst observation of the Greisen-Zatsepin-Kuzmin suppressionThe High Resolution Fly's Eye (HiRes) experiment has observed the Greisen-Zatsepin-Kuzmin suppression (called the GZK cutoff) with a statistical significance of five standard deviations. HiRes' measurement of the flux of ultrahigh energy cosmic rays shows a sharp suppression at an energy of 6 x 10^1...Extensive air showers; Suppression; Energy spectrum; Fluorescence; GZK cutoff2008-03
598 DeTar, CarletonFirst signs for string breaking in two-flavor QCDWe have been examining the phenomenon of string breaking in QCD with two flavors of dynamical staggered quarks. We construct a transfer matrix from a combination of "string" and "two-meson" channels. Preliminary results with low statistics show the expected signs of string breaking.String breaking; Wilson loop; Staggered quarks2000-04
599 Morse, Michael DavidFirst spectroscopic investigation of the 4 d transition metal monocarbide MoCThe first optical spectroscopic investigation of MoC has revealed a complicated vibronic spectrum consisting of about 35 bands between 17 700 and 24 000 cm-1. Analysis has shown the ground state to be the ?=0+ spin?orbit component of a 3?- state that derives from a 10?211?25rr42d 2 configuration. Th...1998
600 Hughes, Kelly T.Flagellar anti-σ factor FlgM actively dissociates Salmonella typhimurium σ28 RNA polymerase holoenzymeThe anti-σ factor FlgM of Salmonella typhimurium inhibits transcription of class 3 flagellar genes through a direct interaction with the flagellar-specific σ factor, σ28. FlgM is believed to prevent RNA polymerase (RNAP) holoenzyme formation by sequestering free σ28. We have analyzed FlgM-media...sigma-factors; transcription; FlgM; Flagellum1998
576 - 600 of 1,952